1. Field of the Invention
This invention relates to a ballast tank for buoyancy compensation, specifically to scuba diving buoyancy control.
2. Background of the Prior Art
In the prior art, buoyancy compensation devices have used compressed air to displace water, which changes buoyancy.
The most common design to date is a buoyancy compensation vest. U.S. Pat. No. 4,000,534 to Cerniway (1977) discloses an inflatable bladder device for scuba. The buoyancy compensator vest is based on the principal of displacement through compressed air, supplied by the divers breathable compressed air tank.
Due to the flexible design of the vest, changes of depth in the water become uncontrollable. For example, if a diver is trying to hold neutral buoyancy at a particular depth and inhales, he will ascend a short distance due to the expansion of air in the chest cavity. Due to the divers ascent in the water, the ambient water pressure decreases, therefore the air in his vest expands; this turns into a compounding effect that will send the diver into an uncontrollable ascent to the surface which can cause life threatening injuries. All of the buoyancy compensators heretofore known suffer from a number of disadvantages:
(1) Previous buoyancy compensators do not offer the diver buoyancy control because they operate on compressed air and air is compressible;
(2) The source of air for buoyancy comes from the breathable air supply, which greatly decreases the divers bottom time, and also the diver's sole source of life support;
(3) Descent is also a problem with the present day buoyancy compensators, the increase in water pressure compresses the air in the buoyancy compensator vest and causes the diver to descend uncontrollably, in which he can either descend to dangerous, life threatening depths, or hit the ocean floor and damage coral reefs; and,
(4) Since the vest is filled with air it is also very cumbersome and binding.